Nevada law enforcement officials investigating a sexual-assault accusation against the soccer star Cristiano Ronaldo have requested a sample of the player’s DNA from the Italian authorities, the Las Vegas Metropolitan Police Department confirmed Thursday evening.

Mr. Ronaldo, a Portuguese wing and five-time world player of the year, plays in Italy for the powerhouse club Juventus.

“The LVMPD is taking the same steps in this case as in any other sexual assault to facilitate the collection of DNA evidence,” Laura Meltzer, a spokeswoman for the Las Vegas police, said in a statement. The department declined to give any additional information about the investigation.

Investigators are seeking the DNA sample as part of a recently reopened investigation into accusations by an American woman, Kathryn Mayorga, who said Mr. Ronaldo raped her in a Las Vegas hotel room in 2009 and later paid her $375,0000 for her silence.

“Mr. Ronaldo has always maintained, as he does today, that what occurred in Las Vegas in 2009 was consensual in nature, so it is not surprising that DNA would be present, nor that the police would make this very standard request as part of their investigation,” one of Ronaldo’s lawyers, Peter S. Christiansen, said in a statement Thursday.

Juventus declined to comment.

Mr. Ronaldo and his lawyers repeatedly denied the rape accusation when it first emerged in October; Mr. Ronaldo labeled them “fake news” in a video posted on one of his social media accounts, and at one point his lawyers threatened to sue the German newsmagazine that was the first to publish Mayorga’s accusations.

The magazine, Der Spiegel, said it had obtained confidential documents related to the case, and the purported payment to settle it, from the shadowy whistle-blower platform Football Leaks. Around the same time, the Las Vegas Metropolitan Police Department said it had reopened its investigation into the alleged rape, following up on information it said had been provided to them by the victim.

A number of the documents Ms. Mayorga’s lawyers say support her claim were published by Der Spiegel, which also published a lengthy interview with Ms. Mayorga. Mr. Ronaldo’s lawyers described the publication of the documents, which included a questionnaire Der Spiegel said detailed events that occurred in a suite at the Palms hotel almost a decade ago, as “blatantly illegal.”

Mr. Ronaldo, now 33, was a star at England’s Manchester United when he met Ms. Mayorga, now 35, at a Las Vegas nightclub in 2009, just before his record-breaking transfer to Real Madrid. He invited her and others to his suite in the early hours of June 13, 2009, she said.

According to her lawsuit, Ms. Mayorga reported the assault to the police later that day and received a medical examination, during which evidence was collected in what is sometimes known as a rape kit. The Las Vegas police have acknowledged that Ms. Mayorga filed a report and was examined, but the police said she did not name her attacker at that time. The case was reopened at Ms. Mayorga’s request in September.

News of the warrant came two days after a second woman, Jasmine Lennard, an English model and reality television star who previously wrote a tell-all about her relationship with Mr. Ronaldo, accused him of violent behavior in a series of posts on Twitter.

In more than a dozen posts, Ms. Lennard said Mr. Ronaldo had threatened to “have me kidnapped and have my body cut up and put in a bag and thrown in a river” if she dated somebody else. She also tweeted offers of help to Ms. Mayorga’s lawyers.

She did not share the “hundreds of messages” she said she had kept, however, and later deleted her Twitter account. In a statement provided to a British newspaper, Mr. Ronaldo’s legal team said the player had never had contact with Ms. Lennard, and would take “appropriate legal action in due course.”

Ms. Lennard could not be reached for comment on her accusations.

Larissa Drohobyczer, a lawyer for Ms. Mayorga, confirmed in an email that she had spoken to Ms. Lennard. She did not have any details of the Las Vegas police investigation, but added: “The issuance of the warrant for Ronaldo’s DNA shows that the LVMPD is taking this investigation seriously.”

In the months since the reports in Der Spiegel, which came shortly after Mr. Ronaldo’s move from Real Madrid to Juventus in a deal worth more than $114 million, Mr. Ronaldo has tried to brush aside the scandal by focusing on his game — he leads the Italian league in scoring with 14 goals — and promoting his brand.